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[GlobalISel] Fix choice of instruction selector for AArch64 at -O0 with -global-isel=0

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Commit rL347861 introduced an unintentional change in the behaviour when
compiling for AArch64 at -O0 with -global-isel=0. Previously, explicitly
disabling GlobalISel resulted in using FastISel but an updated condition
in the commit changed it to using SelectionDAG. The patch fixes this
condition and slightly better organizes the code that chooses the
instruction selector.

Fixes PR40131.

Differential Revision: https://reviews.llvm.org/D56266


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@350626 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Petr Pavlu
2019-01-08 14:19:06 +00:00
parent d7b7319bc2
commit 7885d2ca5a
2 changed files with 58 additions and 12 deletions
Download Patch File Download Diff File Expand all files Collapse all files
lib/CodeGen/TargetPassConfig.cpp
+23 -12
View File
@@ -755,22 +755,33 @@ void TargetPassConfig::addISelPrepare() {
bool TargetPassConfig::addCoreISelPasses() {
// Enable FastISel with -fast-isel, but allow that to be overridden.
TM->setO0WantsFastISel(EnableFastISelOption != cl::BOU_FALSE);
if (EnableFastISelOption == cl::BOU_TRUE ||
(TM->getOptLevel() == CodeGenOpt::None && TM->getO0WantsFastISel() &&
!TM->Options.EnableGlobalISel)) {
// Determine an instruction selector.
enum class SelectorType { SelectionDAG, FastISel, GlobalISel };
SelectorType Selector;
if (EnableFastISelOption == cl::BOU_TRUE)
Selector = SelectorType::FastISel;
else if (EnableGlobalISelOption == cl::BOU_TRUE ||
(TM->Options.EnableGlobalISel &&
EnableGlobalISelOption != cl::BOU_FALSE))
Selector = SelectorType::GlobalISel;
else if (TM->getOptLevel() == CodeGenOpt::None && TM->getO0WantsFastISel())
Selector = SelectorType::FastISel;
else
Selector = SelectorType::SelectionDAG;
// Set consistently TM->Options.EnableFastISel and EnableGlobalISel.
if (Selector == SelectorType::FastISel) {
TM->setFastISel(true);
TM->setGlobalISel(false);
} else if (Selector == SelectorType::GlobalISel) {
TM->setFastISel(false);
TM->setGlobalISel(true);
}
// Ask the target for an instruction selector.
// Explicitly enabling fast-isel should override implicitly enabled
// global-isel.
if (EnableGlobalISelOption == cl::BOU_TRUE ||
(EnableGlobalISelOption == cl::BOU_UNSET &&
TM->Options.EnableGlobalISel && EnableFastISelOption != cl::BOU_TRUE)) {
TM->setGlobalISel(true);
TM->setFastISel(false);
// Add instruction selector passes.
if (Selector == SelectorType::GlobalISel) {
SaveAndRestore<bool> SavedAddingMachinePasses(AddingMachinePasses, true);
if (addIRTranslator())
return true;
test/CodeGen/AArch64/GlobalISel/gisel-commandline-option-fastisel.ll
+35
View File
@@ -0,0 +1,35 @@
; REQUIRES: asserts
; RUN: llc -mtriple=aarch64-- -debug-pass=Structure %s -o /dev/null 2>&1 \
; RUN: -verify-machineinstrs=0 -O0 -global-isel=false -debug-only=isel \
; RUN: | FileCheck %s --check-prefixes=DISABLED,FASTISEL
; RUN: llc -mtriple=aarch64-- -debug-pass=Structure %s -o /dev/null 2>&1 \
; RUN: -verify-machineinstrs=0 -O1 -global-isel=false -debug-only=isel \
; RUN: | FileCheck %s --check-prefixes=DISABLED,NOFASTISEL
; RUN: llc -mtriple=aarch64-- -debug-pass=Structure %s -o /dev/null 2>&1 \
; RUN: -verify-machineinstrs=0 -O0 -fast-isel=false -global-isel=false \
; RUN: -debug-only=isel \
; RUN: | FileCheck %s --check-prefixes=DISABLED,NOFASTISEL
; RUN: llc -mtriple=aarch64-- -debug-pass=Structure %s -o /dev/null 2>&1 \
; RUN: -verify-machineinstrs=0 -O1 -fast-isel=false -global-isel=false \
; RUN: -debug-only=isel \
; RUN: | FileCheck %s --check-prefixes=DISABLED,NOFASTISEL
; Check that the right instruction selector is chosen when using
; -global-isel=false. FastISel should be used at -O0 (unless -fast-isel=false is
; also present) and SelectionDAG otherwise.
; DISABLED-NOT: IRTranslator
; DISABLED: AArch64 Instruction Selection
; DISABLED: Expand ISel Pseudo-instructions
; FASTISEL: Enabling fast-isel
; NOFASTISEL-NOT: Enabling fast-isel
define void @empty() {
ret void
}